Pressurized communication cable and system

ABSTRACT

Disclosed herein is a pressurized communication system and a novel-type cable forming a significant component of the pressurized system. Such a system is composed of a plurality of spaced-apart enclosures, which may contain means for transmitting, modifying, amplifying or repeating an electrical signal. Each of the enclosures is connected one to another by a novel-type cable, which comprises a plastic sheath surrounding and defining a first cable portion containing electrical conductors and a second cable portion containing a longitudinally disposed cavity adapted for the transport of a fluid (dry gas). The electrical conductors of the cable are in electrical connection with a transmitter, repeater, modifier, or amplifying means and the fluid carrying cavity portion of the cable may be in pneumatic communication with the inside of the enclosure and physically separable either in whole or in part from that portion of the cable containing the electrical conductors.

United States Patent [72] Inventor Walter T. Kennedy 1120 Prescott Road,Newton Square, Pa. 19073 [21] Appl. No. 797,490 [22] Filed Feb. 7, 1969[45] Patented Mar. 16, 1971 54] PRESSURIZED COMMUNICATION CABLE ANDSYSTEM 12 Claims, 6 Drawing Figs.

- [52] U.S.Cl. 174/11, 174/47, 174/70 [51] Int.Cl. 1101b 7/00 [50]FieldofSearch 174/8,11, 14, 15 (C), 16, 18, 24,41,47,68, 70, 70.1, 70.4,115, 113.2, 12, 13; 340/320; 339/15, 16; 179/170, 179

I [56] References Cited UNITED STATES PATENTS 2,063,703 12/1936Siddalletal. 174/47X 2,550,021 4/1951 Rappl 174/47UX 2,722,237 11/1955Rosel 174/47UX 2,776,385 1/1957 Modrey... 174/47UX 3,143,641 8/1964 Wise174/47X w 9 cog 23 9 FOREIGN PATENTS 129,667 9/1932 Austria 174/15(C)916,363 8/1946 France 174/15(C) 285,920 9/1968 Australia 174/15(C)1,222,734 l/1960 France 174/47 902,988 2/1954 Germany 174/15(C) 206,441l/1968 U.S.S.R 174/47 Primary Examiner Laramie E. Askin Attorney-Roy B.Moffitt means for transmitting, modifying, amplifying or repeating anelectrical signal. Each of the enclosures is connected one to another bya novel-type cable, which comprises a plastic sheath surrounding anddefining a first cable portion containing electrical conductors and asecond cable portion containing a longitudinally disposed cavity adaptedfor the transport of a fluid (dry gas). The electrical conductors of thecable are in electrical connection with a transmitter, repeater,modifier, or amplifying means and the fluid carrying cavity portion ofthe cable may be in pneumatic communication with the inside of theenclosure and physically separable either in whole or in part from thatportion of the cable containing the electrical conductors.

Patented March 16,1971 3,571,486

3 Sheets-Sheet 1 FIGURE 2 IN TOR WALTER ENNEDY 7 lad/q:

ATTORNEY Patented Mai'ch 16, 1971 1 3,571,486

3 Sheets-Sheet 2 INVENT WALTER T. KE I EDY ATTORNEY Y FRESSUREZEDCOMMUNICATIGN CAME AND SYSTEM This invention relates to pressurizedcommunication systems and more particularly to the structure of anovel-type cable and its use in a pressurized communication system. Suchcable as disclosed herein is normally used in low voltage levelapplications as in connection with voice transmission lines(telecommunication lines) or television signal transmission.

in the main, it is the primary purpose and one of the fundamentalobjects of the instant invention to provide a cable structure that canbe used either aerially or underneath the soil, which can give rise to aunique pressurized system. For example, within the scope of coaxialcable transmission systems using either an expanded or unexpandedpolyethylene dielectric, conventional cable construction precludes apressurized system that uses any part of the cable for gas passage. Inview of the fact that the instant invention visualizes a tube additionintegrally fixed to a coaxial cable, dry air or gas can be forced underpressure into, through and out of equipment enclosures connectedtogether by the cable itself. Such a system, using the novel type cabledisclosed herein, enables the creation and maintenance of a stabileatmosphere and pressure within enclosures housing such devices as CATVamplifiers, telephone repeater units, and any pole mounted orunderground equipment whose proper operating characteristics arestabilized or enhanced by dry gas pressurization.

In the area of multiconductor communication cables, as distinguishedfrom coaxial cable, the structure of the noveltype cable allows thetransmission of dry gas through that part of the cable carrying theelectrical conductors as well as that cable part especially designed forsuch transport to and into desired enclosures. Thus, gas may be used topressurize such enclosures, but the gas also may be used to purge waterthat may collect in a cavity where insulated'electrical conductors areconfined. Gas can be forced from each enclosure into that longitudinalcavity in which a plurality of insulated conductors are disposed;therefore, water collecting in said last-mentioned cavity is forcedtowards the middle of each cable section between enclosures. A valveadapted to open and close automatically by the degree of moisture orpressure within that cavity of the cable enclosing insulated electricalconductors may be inserted in the cable between any two enclosures. Sucha valve is optimumly placed at the point in the conductor carryingportion of cable section where pneumatic pressure is equal from bothdirections. Thus, each cable section can be automatically purged ofmoisture when such moisture reaches an undesirable level. Furthermore,enclosures that need to be bypassed and not pressurized can be in asimple and inexpensive manner.

The foregoing delineates the objects of the instant invention, otherobjects, advantages and features of the present invention will becomeapparent from he following detailed description, one embodiment of whichis present in conjunction with thedrawings, in which:

FIG. ll shows a cross section of a figure 8 Cable, wherein the plasticsheath of the cable describes two cavities, one such cavity beinglongitudinally disposed. and essentially unoccupied and the other suchcavity containing an outside and inside conductors separated by aplastic dielectric;

MG. 2 shows essentially the same subject matter as FIG. 1 except thatFIG. ll discloses a metal tube disposed in the essentially unoccupiedcavity whereas FIG. 2 uses a plastic tube disposed in that cavity;

FIG. 3 is a fragmentary view of a cross section of a FlG. 8 Cable,wherein there is shown two cavities longitudinally disposed in theplastic sheath, one such cavity containing a metal tube and the othersuch cavity containing a plurality of electrical conductors;

FIG. 4 shows a plastic sheath containing three longitudinally disposedindefinite length cavities, the plastic portion of an integral sheathsurrounding said cavities being connected one to another by a plasticweb, one of said cavities being essentially unoccupied but containing ametal tube longitudinally disposed therein, another of said cavitiesbeing occupied by a centrally disposed electrical conductor nestedinside of a tubular outside electrical conductor, these conductorsseparated one from another by a plastic dielectric, and the third cavitybeing essentially occupied by a messenger cable which is adapted tosupport the entire cable;

FIG. 5 shows a pressurized communication system that includesspaced-apart enclosures containing amplifying or repeater meanspneumatically and electrically connected together by a means of thenovel-type cable disclosed herein; and,

HO. 6 shows a cross section along lines 6-6 of FIG. 5.

Turning now to FIG. 1, this drawing shows in cross section the structureof an indefinite length cable indicated by element 1. A tubular conduit3 is surrounded by an impervious plastic sheath 2 forming an essentiallyunoccupied cavity 4 longitudinally disposed in the cable sheath andadapted to transport a fluid. A web 19 connects this fluid-carryingportion of the cable with that portion of theplastic sheath 2 thatsurrounds electrical conductors 5 and 7, which are, in this particularembodiment, a tubular outer conductor 5, usually made of metal such asaluminum or copper and the like, and center conductor 7, centrallydisposedinside of tubular electrical conductor 5. Center conductor 7 isinsulated from outer electrical conductor 5 by dielectric 6, which canbe either expanded or unexpanded plastic, the composition of which canbe the same as or different from that of plastic sheath 2. In effect,elements 5, 6, and 7 make up a coaxial cable surrounded by an outerplastic sheath 2, this outer plastic sheath being joined by web 19 tothe same plastic sheath 2 which surrounds a metal conduit or tubularmeans 3, the latter being adapted to carry a fluid in the longitudinaldirection. It is to be understood, however, that metal tube 3 of FIG. I,as well as plastic tube 3' of FIG. 2, can be deleted. In this case,cavity 4 formed by plastic sheath 2 is used to transport a fluid in alongitudinal direction.

The figure 8 Cable shown by element 8 of FIG. 2 is essentially the sameas that shown by element 1 in FIG. 1, except for the fact that the metaltube 3 of FIG. 1 has been replaced by a plastic tube 3'. Usually, butnot absolutely necessary, this plastic tube 3' is of a differentcomposition from that forming web 19 and plastic sheath 2. For example,tube 3', as well as plastic sheath 2, can be made from polyethylene,either of the high or low density type, polyvinyl chloride,polycarbonates, fluorinated hydrocarbons (Teflon) and nylon. In someinstances, it may be desirable to have plastic tube 3 filled with afinely divided filler such as metal or a silica material (quartz, groundrock and the like) in order to make this particular plastic tubeabrasive and resistant to attack from outside elements, such as gophers,tools of careless workmen, and intentional vandalism.

Elements 1 and 8 of FIGS. 1 and 2 are made from a coaxial cable portioncomposed of elements 5, 6, and '7 integral, via sheath 2 and web HQ,with a cable containing a longitudinally disposed cavity 4, adapted forthe transport of a fluid, created by elements 3 or 3'. l-Ieretofore,there has been a need for such a cable like i and 8, but cablefabricators have always attempted to position the fluid-carrying,longitudinally disposed cavity 4 in the dielectric 6. Such a positioningof this cavity 5 in that particular area 6 disrupts the electricalcharacteristics of the coaxial cable. Thus, complicated electricaldesign problems were created in an effort to recoup those electricalproperties normally incident to coaxial cable structure.

Shown in FIG. 3 is a figure 8 Cable having a structure much like that ofthe figure 8 Cables in FIGS. 1 and 2. In fact, from web 19 upwards, thestructure of the cable 9, shown in FIG. 3, is the same as the cable l,shown in FIG. l. Thus, no further discussion of this particularstructure is deemed necessary. The balance of cable 9 of FIG. 3, fromweb 19 downward, resembles the balance of the cable 1 and 8, shown inFEGS. l and 2 respectively, only in the sense that there is a cavity inwhich electrical conductors are disposed. This cavity 20 is filled withthree elements, namely metal tape it), plastic tape ill, and insulatedelectrical conductors is. The metal tape, the extremities of whichoverlap one another to form a circular configuration, can be either ametal tape per se made from steel, aluminum or copper or alloys thereofor it can be a plastic-coated tape much like that shown in the U.S. Pat.to Jachimowicz (No. 3,233,036). Plastic tape 11 can be either anoncorrugated polyethylene terephthalate tape or corrugated tape such asthat shown and described in Roberts US. Pat. No. 3,244,799. Of course,the polyethylene terephthalate composition of plastic tape 11 isexemplary only and other compositions could be used as equivalents suchas polyethylene, PVC, polycarbonate, halogenated hydrocarbons, andnylon.

Cable 13, shown in FIG. 4, is a variation of that cable structure 1shown in FIG. 1. An additional web 19 has been added to the cablestructure 1 of FIG. 1 and this additional web is integral with plasticsheath 2, which completely surrounds a messenger cable 12. Thislast-mentioned messenger cable is usually made up of a plurality ofmetal strands so designed, woven, and structured so as to be adapted tocarry the entire weight of the cable. Thus, cable 3 in service is strungusing the messenger cable 12 in an aerial disposition, the messengercable 12 being structurally adapted to carry not only its own weight,but the weight of the balance of the cable as well. This messengerportion of cable 13 shown in FIG. 4 is essentially the same as themessenger cable portion shown in U.S. Pat. to Pusey, No. 3,267,201 andcan be formed in the same manner as disclosed in this particular priorart disclosure.

FIG. 5 shows a portion of a pressurized telecommunications system withelements 15, 15 and 15" representing enclosures in which there aredisposed amplifying, modifying, repeating, or splicing means, whicheither amplify repeat, or connect the signal transmitted alongelectrical conductors inside of the cable represented by component 22.The line 66 indicates a cross section through the cable and valve means17, which is located approximately midway between two enclosures l5 and15. As previously indicated, the cable connecting enclosures 15, 15',and 15" are interconnected one to another by means of a cable, thatcable having two portions indicated by fluid-carrying portion 21 andelectrical-carrying portion 22.

In FIG. 6, element 16 shows the cross section along line 6- 6, whichpasses through valve 17 The cable structure shown in 16 is essentiallythe same as that of element 9 of FIG. 3, except for the addition ofvalve 17. This particular valve can be either pressure or moisturesensitive in the sense that it will respond, i.e., open, when a givenpressure is achieved or when a predetermined moisture content has beendetected. In the cable system 14, of FIG. 5, cable 16 of FIG. 6 is used.Both cavity 4, [cable portion 21] and that cavity created by metal tapenot otherwise occupied by insulated electrical conductors 13, [cableportion 22] are under pressure and are thus used to transmitlongitudinally a fluid (dry gas for example). Thus, in this embodiment,both cavities 4 and 23 would carry a dry gas under pressure.

Gas pressure in cavity 4 is envisioned to be greater in mostcircumstances than that in cavity 23. Assuming for example that the airor gas under pressure flows from left to right (FIG. 5), the totalpressure in enclosure would be the sum of the pressures in cavity 23plus 4 and thus would be greater than that in the individual cableportions 21 and 22 defining respectively cavities 4 and 23. Therefore,that in cavity 23 upstream therefrom. Hence, some of the dry gas inenclosure 15 will flow to the left, consequently forcing any condensedwater in cavity 23 towards cable valve 17. When a predetermined pressureor moisture content is detected by valve 17, this valve opens and cavity23 is thus purged of collected moisture. Gas pressure in enclosure 15forces dry gas in the rightwardly direction in cable 22 [cavity 23]consequently forcing moisture condensation towards valve 17 and itssubsequent expulsion in an automatic manner from the cable system 14.

In FIG. 5, it will be noted that cable portion 22 carrying theelectrical elements of the cable is separated from cable portion 21 justbefore cable portions 21 and 22 enter enclosures 15 and 15'. Usually,separation takes place in web 19 and is for ease of attachment of thecable to the enclosures. Previous discussion of FIG. 5 employed thatcable structure 16 shown in FIG. 6 as the cable portion of thepressurized system; however, cable structures [13, FIG. 4]; [9, FIG. 3];[8, FIG. 2]; and [1, FIG. 1]can all be used as that cable portion of thepressurized system as shown in FIG. 5, it being understood thatpressurized gas would exist only in cavity 4 in these specificembodiments.

One of the great advantages of the cable structure shown by elements 1and 8 of FIGS. 1 and 2 respectively, is that fluidcarrying cavity 4 canbe used to pressurize enclosures such as 15, 15 and 15" in whichamplifiers, repeaters, modifiers, splitters, or splices are located. Inthe technological area of telecommunications, enclosures 15, 15' and 15"may be what is called a splice case and they contain load coils andother well-known apparatus incident to telecommunications systems.Therefore, a splice case which is an enclosure, can be pressurized suingthis cable with relative ease.

Previous discussion has emphasized the use of the cable structures forpurposes of transmitting data from one point to another; however, thecables shown in the drawings, can be used in conjunction with electricalpower transmission and the cavity integral with such power-conveyingelectrical conductors can be used to moderate temperature and/ormoisture control of remote transformers, breakers and other power systemfacilities. Such an application of the instant cable structure to thefield of power transmission is quite obvious from the instant disclosureand one of only ordinary skill in the art only need the disclosurepreviously set forth before him to construct a power-transmittingfacility that can be and is pressurized for various and sundry purposes.

From the foregoing, it is believed that the invention may be readilyunderstood by those skilled in the art so that further descriptions areunnecessary. It being born in mind that numerous changes may be made inthe details disclosed without departing from the spirit of the inventionas set forth in the following claims.

I claim:

1. A cable comprising an essentially impervious plastic sheath ofindefinite length which surrounds at least two spaced-apart,longitudinally disposed cavities, one of said cavities being occupied bya center conductor circumscribed longitudinally by a dielectric materialwhich is in turn circumscribed by a second conductor and the othercavity being essentially unoccupied and adapted for the longitudinaltransport of a fluid therethrough, that portion of the plastic sheathlying between and connecting the plastic surrounding said first andsecond cavities being configurated so as to permit division of saidplastic sheath into at least two such sheaths each containing one ofsaid cavities.

2. A cable as defined in claim 1 wherein said sheath defines a thirdcavity in which is disposed a means for structurally supporting theentire weight of said cable.

3. A cable as defined in claim 1 wherein that cavity adapted for thelongitudinal transport of a fluid contains a tubular meanslongitudinally disposed therein.

4. A cable'as defined in claim 3 wherein said tube is constructed of aplastic of a composition differing from the plastic sheath.

5. A cable as defined in claim 3 wherein said tube is constructed of ametal.

6. A pressurized communications system comprising a plurality ofspaced-apart enclosures containing means for modifying an electricalsignal connected one to another by a cable comprising a plastic sheathdefining a first cable portion containing electrical conductors and asecond cable portion containing a longitudinally disposed cavity adaptedfor the transport of a fluid, the electrical conductors being inelectrical connection with said modifying means and said cable secondportion being in pneumatic communication with the inside of saidenclosure.

7. A communications system as defined in claim 6 wherein said secondcable portion is physically separated from said first cable portion justbefore it reaches the outside surface of the sidewalls of the enclosureand terminates just after passing into the interior of said container.

8. A cable comprising an essentially impervious plastic sheath defininga first cable portion having a first longitudinally disposed cavity, inwhich a plurality of insulated electrical conductors are contained, anda second cable portion having a second cavity adapted for thelongitudinal transport of a fluid and a valve means disposed in saidfirst cavity adapted to establish communications between the interior ofsaid first cavity and that atmosphere in contact with the outsidesurface of said plastic sheath.

9. A pressurized communication system comprising a plurality ofspaced-apart means for modifying an electrical signal, each of saidmeans being enclosed in a container having sidewalls and connected oneto another by a cable composed of a plastic sheath defining a firstcable portion having a first longitudinally disposed cavity in which aplurality of insulated electrical conductors are contained and a secondcable portion having a second longitudinally disposed cavity adapted forthe longitudinal transport of a fluid, the electrical conductors of saidcable first portion being in electrical connection with said modifyingmeans and said first and second cable portion being in pneumaticcommunication with the inside of said container so that pressurizedfluid may be introduced into said container from said first and secondcable portions.

10. A communication system as defined in claim 9 wherein a'valve isdisposed in said second cable portion between the container meansadapted for the expulsion of water accumulated in that space of saidfirst cavity not otherwise occupied by the insulated electricalconductors.

11. A communications system as defined in claim 10 wherein said valve isresponsive to open at a predetermined pressure.

12. A communications system as defined in claim 10 wherein said valve isresponsive to open at a predetermined moisture content.

1. A cable comprising an essentially impervious plastic sheath of indefinite length which surrounds at least two spaced-apart, longitudinally disposed cavities, one of said cavities being occupied by a center conductor circumscribed longitudinally by a dielectric material which is in turn circumscribed by a second conductor and the other cavity being essentially unoccupied and adapted for the longitudinal transport of a fluid therethrough, that portion of the plastic sheath lying between and connecting the plastic surrounding said first and second cavities being configurated so as to permit division of said plastic sheath into at least two such sheaths each containing one of said cavities.
 2. A cable as defined in claim 1 wherein said sheath defines a third cavity in which is disposed a means for structurally supporting the entire weight of said cable.
 3. A cable as defined in claim 1 wherein that cavity adapted for the longitudinal transport of a fluid contains a tubular means longitudinally disposed therein.
 4. A cable as defined in claim 3 wherein said tube is constructed of a plastic of a composition differing from the plastic sheath.
 5. A cable as defined in claim 3 wherein said tube is constructed of a metal.
 6. A pressurized communications system comprising a plurality of spaced-apart enclosures containing means for modifying an electrical signal connected one to another by a cable comprising a plastic sheath defining a first cable portion containing electrical conductors and a second cable portion containing a longitudinally disposed cavity adapted for the transport of a fluid, the electrical conductors being in electrical connection with said modifying means and said cable second portion being in pneumatic communication with the inside of said enclosure.
 7. A communications system as defined in claim 6 wherein said second cable portion is physically separated from said first cable portion just before it reaches the outside surface of the sidewalls of the enclosure and terminates just after passing into the interior of said container.
 8. A cable comprising an essentially impervious plastic sheath defining a first cable portion having a first longitudinally disposed cavity, in which a plurality of insulated electrical conductors are contained, and a second cable portion having a second cavity adapted for the longitudinal transport of a fluid and a valve means disposed in said first cavity adapted to establish communications between the interior of said first cavity and that atmosphere in contact with the outside surface of said plastic sheath.
 9. A pressurized communication system comprising a plurality of spaced-apart means for modifying an electrical signal, each of said means being enclosed in a container having sidewalls and connected one to another by a cable composed of a plastic sheath defining a first cable portion having a first longitudinally Disposed cavity in which a plurality of insulated electrical conductors are contained and a second cable portion having a second longitudinally disposed cavity adapted for the longitudinal transport of a fluid, the electrical conductors of said cable first portion being in electrical connection with said modifying means and said first and second cable portion being in pneumatic communication with the inside of said container so that pressurized fluid may be introduced into said container from said first and second cable portions.
 10. A communication system as defined in claim 9 wherein a valve is disposed in said second cable portion between the container means adapted for the expulsion of water accumulated in that space of said first cavity not otherwise occupied by the insulated electrical conductors.
 11. A communications system as defined in claim 10 wherein said valve is responsive to open at a predetermined pressure.
 12. A communications system as defined in claim 10 wherein said valve is responsive to open at a predetermined moisture content. 